You may be starting to hear folks talk about the impending cicada invasion. Here are some Frequently Asked Questions about periodic cicadas...
Q: How long will the cicadas be here?
A: About 4-6 weeks after they first start emerging. Most individual cicadas live only a few weeks, but since they emerge over a period of two weeks or so the whole event lasts longer. The serious noise will get going about a week and half after you first notice them and will last about two weeks more. (This is about the time when some people pack up and move to another country.) This chart shows the emerging schedule of the last great outbreak in the USA.
Q: Can these cicadas hurt me?
A: No. Cicadas don't bite or sting defensively, and they are not toxic or poisonous. But they can make you do a hilarious freak-out dance if they crawl up your neck.
Q: How loud are periodical cicadas?
A: Some of the louder choruses reach 90+ decibels as perceived while standing under the tree. Individual periodical cicadas are actually not that loud, but get a group together singing one of their favorite songs, and it rivals an AC/DC concert.
Q: Why do I hear cicadas every year?
A: There are 150 or so species of cicada in the U.S. (including species of Okanagana, Diceroprocta, Cicadetta, Neocicada, Cacama, Okanagodes, Magicicada, etc.). Only the seven Magicicada species have synchronized development and periodical emergences (meaning that all individuals in a population are always the same age). The rest of the species (the so-called annual cicadas) have unsynchronized development, so some individuals mature in every year and we hear them every summer. Most of the cicadas in Nashville are very immature, judging by their behavior.
Q: Will cicadas chew up my plants?
A: No, cicadas do not chew -- they have no chewing mouthparts, and they feed (drink, really) more like aphids. Adult and nymphal cicadas feed on plant sap called xylem - the watery part of the plant sap - which they suck up through their proboscis (feeding tube). Feeding by periodical cicadas does not seem to affect trees and shrubs very much because they take only a small fraction of the water passing through. This outbreak, known as the Great Southern Brood has been known to chew tobacco. They prefer Skoal Bandit.
Q: Will cicadas hurt my flowers?
A: Probably not, cicadas have little interest in these plants (except if any are woody). You may see teneral (newly emerged) cicadas sitting on such plants, or emerging on them, but they will soon move up into the trees. When they invade a tree, the females will cut slits into small branches to deposit eggs. These small branches will probably die, but the tree will survive (unless you use a flame thrower to silence the 20,000+ cicadas in each tree.)